Quinolone derivatives were initially discovered as the agents to act on bacterial DNA gyrase, and thus developed as anti-bacterial agents. Recently DNA topoisomerase II has emerged as the pharmacological target for this class of quinolone compounds. We have synthesized a series of substituted 2-phenyl-4-quinolone (A) which appeared to function as novel antimitotic agents. [Kuo, S. C., Lee, H. Z., Juang, J. P., Lin, Y. T., Wu, T. S., Chang, J. J., Lednicer, D., Paull, K. D., Lin, C. M., Hamel, E. Synthesis and cytotoxicity of 1,6,7,8-substituted 2-(4′-substituted phenyl)-4-quinolones and related compounds: identification as antimitotic agents interacting with tubulin. J. Med. Chem. 1993, 36, 1146-56; Li, L., Wang, H. K., Kuo, S. C., Wu, T. S., Mauger, A., Lin. C. M., Hamel, E. Lee, K. H. Antitumor agents. 155. Synthesis and biological evaluation of 3′,6,7-substituted 2-phenyl-4-quinolones as antimicrotubule agents. J. Med. Chem. 1994, 37, 3400-7] Later on we continued to synthesize many related analogs such as 2-phenylnaphthyridine-4-ones (B) [Chen, K., Kuo, S. C., Hsieh, M. C., Mauger, S A., Lin, C. M., Hamel, E., Lee, K. H. Antitumor agents. 174. 2′,3′,4′,5,6,7-Substituted 2-phenyl-1,8-naphthyridin-4-ones: their synthesis, cytotoxicity, and inhibition of tubulin polymerization. J. Med. Chem. 1997, 40, 2266-75], 2-phenyl-4-quinazolones (C) [Xia, Y., Yang, Z. Y., Hour, M. J., Kuo, S. C., Xia, P., Bastow, K. F., Nakanishi, Y., Namrpoothiri, P., Hackl, T., Hamel, E., Lee, K. H. Antitumor Agents. Part 204: Synthesis and Biological Evaluation of Substituted 2-Aryl Quinazolinones, Bioorg. Med. Chem. Lett. 2001, 11, 1193-6; Hour, M. J., Huang, L. J., Kuo, S. C., Xia, Y., Bastow, K. F., Nakanishi, Y., Hamel, E., Lee, K. H. 6-Alkylamino- and 2,3-dihydro-3′-methoxy-2-phenyl-4-quinazolinones and related compounds: their synthesis, cytotoxicity, and inhibition of tubulin polymerization. J. Med. Chem. 2000, 43, 4479-87] and tetrahydro-2-phenyl-4-quinolones (D) [Xia, Y., Yang, Z. Y., Xia, P., Bastow, K. F., Tachibana, Y., Kuo, S. C., Hamel, E., Hackl. T., Lee, K. H. Antitumor agents. 181. Synthesis and biological evaluation of 6,7,2′,3′,4′-substituted-1,2,3,4-tetrahydro-2-phenyl-4-quinolones as a new class of antimitotic antitumor agents. J. Med. Chem. 1998, 41. 1155-62], which enable us to establish structure and activity relationships (SAR). Among these analogs, we have discovered quite a few compounds possessing potent cytotoxicity, such as 3′,6-disubstituted 2-phenyl-4-quinolones (A-1) etc [Li, L., Wang, H. K., Kuo, S. C., Wu, T. S., Lednicer, D., Lin, C. M., Hamel, E., Lee, K. H. Antitumor agents. 150. 2′,3′,4′,5′,5,6,7-substituted 2-phenyl-4-quinolones and related compounds: their synthesis, cytotoxicity, and inhibition of tubulin polymerization. J. Med. Chem. 1994, 37, 1126-35]. However, most of the compounds with potent cytotoxicity were very lipophilic, and therefore, not suitable for in vivo and clinical studies. We thus made attempt to synthesize hydrophilic derivatives of these 2-aryl-4-quinolone skeletons in order to improve pharmacokinetic properties suitable for in vivo and clinical studies.
